Max safe boost? [Merged 10-6]

[Turbolaser]

Is it safe to do the boost contol solenoid mod on a stock 1G?

 

[red97tib]

I have seen this issue pop around the forums quiet a bit, but never a straight answer come of it. Everybody always lays out how much boost they want to run and the supporting mods and such then like 5 people pop in and talk about the auto tranny not being able to hold up. I have never seen a solid number but it's above 18 psi, I know that much.

 

[RallyEclipse98]

I take it your engine is built and now your just wondering what your tranny can take? I would slap a tranny cooler on and worry about your engine setup breaking, not your tranny. If your transmission does give out, beef up the new auto transmission you replace it with or do a 5-spd swap.

 

[tcavenger99]

yes my engine is fully built. I plan to do a 5 speed swap this winter yet till then i am automatic .i am presently running 10 psi and the motor feels great yet the tranny is kind of iffy. just thought i would ask this question because i want to drive my car all summer then swap in winter

 

[psycho]

Personally, every auto that I have seen boosted has failed with less than moderate power levels. If you plan on keeping it for a while, I would suggest a decent sized transmission cooler. And don't do burn outs.

 

[91tizzy]

I know the only problem with the auto awd tranny's is the endclutches will go with too many abusive launches...other than that there actually pretty beefy auto's...converter can hold up suprisingly well...Im boosting on a stock auto awd setup with 153,xxx miles....all you can do is drive it and use your best judgement and see what happens....maintenance maintenance maintenance

 

[twack]

I run 28psi daily on a 50trim pte turbo on a stock auto tranny with 120k miles on it. holding up great.

 

[91tizzy]

I run 28psi daily on a 50trim pte turbo on a stock auto tranny with 120k miles on it. holding up great.

haha this right here is freakin killer to hear.....tell all the naysayers to shove it

 

[TSIMonsteR]

I run 28psi daily on a 50trim pte turbo on a stock auto tranny with 120k miles on it. holding up great.

The OP is a 420a car... different transmission

 

[JDMath]

get bigger injector and something to tune it! and a logger to keep an eye on your engine, upgrade your fuel pump to walbro 255

 

[1stGenTSi]

get bigger injector and something to tune it! and a logger to keep an eye on your engine, upgrade your fuel pump to walbro 255

Def get 550's or 650's and if you don't have a lot to spend just get a walbro 190 and rewire it. With a 255 you will need to spend an extra ~$250 for an AFPR and install accessories. With the 650cc injectors you will have a little room to grow and still be able to get them dialed in reasonably well with just an AFC. Def get a wideband and logger too.

 

[JDMath]

Def get 550's or 650's and if you don't have a lot to spend just get a walbro 190 and rewire it. With a 255 you will need to spend an extra ~$250 for an AFPR and install accessories. With the 650cc injectors you will have a little room to grow and still be able to get them dialed in reasonably well with just an AFC. Def get a wideband and logger too.

i think the stock fpr can handle that ... but for sure its a good idea too a afpr

 

[1stGenTSi]

i think the stock fpr can handle that ... but for sure its a good idea too a afpr

Stock fpr and wally 255 is not a good idea, even if you can get it to idle ok.

 

[WKSDSM]

I ve been told 8, but what is the most boost I can run stock and be safe? I not looking for more than 12 at the most . I ve got a 90 gsx 180,000.

 

[FORMONTOYA]

Depends on the condition the car is in...could be 20+, could be 2. Nobody on here can truly give you that information until more is known.

 

[4g63Powered]

The accepted norm is 14psi on stock fuel system. Now, whether or not your high milage engine can stand that is another issue.

You can do a compression test and a leakdown test to determine how healthy your engine is, and go from there. Compression tests are stupidly easy to do and give you a nice starting point. You should be able to rent/borrow the tester from a local auto parts store if you dont know someone with one already.

Stock pressure is between 8 and 10psi, so that's why you've been told that.

 

[ove_98 TSI]

I would say not to go above 14 PSI on the stock fuel system, all mantinence should be done before raising boost

 

[Captainredeyez]

Also if you are going to raise your boost, you should rewire the fuel pimp first.

 

[jrohner]

You need to get a logger to see what is going on. That's how you know how much boost you can safely run. If you already have a laptop or a palm, you just need a cable and can find free software online such as tmolog and mmcd.

 

[throwedgsx]

I agree with 4g63powered. See how healthy your motor is by doing a compression test and/or leakdown test. A safe range is 5 psi between cylinders and no lower than 150psi i believe. Someone correct me if i'm wrong. If your numbers don't match that criteria then it's rebuild time.

 

[knochgoon24]

I agree with 4g63powered. See how healthy your motor is by doing a compression test and/or leakdown test. A safe range is 5 psi between cylinders and no lower than 150psi i believe. Someone correct me if i'm wrong. If your numbers don't match that criteria then it's rebuild time.

I've heard no more than 10% difference between cylinders.

150psi*10%= 15psi.

 

[DSM4me44]

The accepted norm is 14psi on stock fuel system. Now, whether or not your high milage engine can stand that is another issue.

You can do a compression test and a leakdown test to determine how healthy your engine is, and go from there. Compression tests are stupidly easy to do and give you a nice starting point. You should be able to rent/borrow the tester from a local auto parts store if you dont know someone with one already.

Stock pressure is between 8 and 10psi, so that's why you've been told that.

I agree. I ran 14psi all day long stock. I can't speak for everyone nor do I speak for every case, but I have yet to see someone around this area blow up a motor on a stock turbo with lower boost like that on a STOCK turbo. I would hit fuel cut once and awhile on 14psi with not fuel management or pump rewire.

 

[throwedgsx]

I've heard no more than 10% difference between cylinders.

150psi*10%= 15psi.

It could be 15psi difference. That just seams a little high. I don't think i'd let my numbers fluctuate that much

I agree. I ran 14psi all day long stock. I can't speak for everyone nor do I speak for every case, but I have yet to see someone around this area blow up a motor on a stock turbo with lower boost like that on a STOCK turbo. I would hit fuel cut once and awhile on 14psi with not fuel management or pump rewire.

Engine failure happens because of abuse and neglect to an unhealthy engine. Not because of the size of the turbo

 

[hdoerr]

To the OP, With a logger you can monitor injector duty cycle which should not exceed 90% to be safe. On a 1G zero counts of knock is optimal but the ecu will not retard timing until it sees more than 7 counts. Running manifold pressure to the waste gate and logging some pulls will give you an idea of how much more you can turn up the boost but on mostly stock equipment you will see that your car can't do much more safely. All of the suggestions above considered I would start by doing a comp test and getting a logger. It is such a hard task to answer this question because every single car has different weak spots and so many parameters factor into the correct answer that only you can determine it. Hope that helps. P.S. Finding local DSM'ers will be your best option.

 

[WKSDSM]

Thanks to all.

 

[91tizzy]

he has a first gen so the compression could be as low as about 125 before rebuild time. 121 says haynes